Yes, it can be. Specialized knowledge does not require that the employee be the only holder; it requires that the knowledge be specific to the petitioner's product or processes and not commonly held in the industry.
The comparison is with the industry, not with the two colleagues
Hypothetical example: The test asks whether the Portugal Cove-St. Philip's developer's knowledge is of the company's own product, research, equipment, techniques or procedures, and whether it is distinct from what is generally available in the aquaculture-technology industry. A company that trained two other staff on its calibration firmware has not diluted the knowledge into general skill; it has documented that the knowledge is proprietary and taught internally. What weakens a file is evidence that the knowledge is really a widely available skill dressed up in company terminology, or that the developer's U.S. task could be performed by any competent embedded engineer after reading the manual. The petition should therefore describe the specific system, the developer's role in creating it, the internal training that transmits it, and why the U.S. affiliate cannot readily hire the knowledge locally. Salary level and years of experience are supporting facts, not the test.
Hypothetical example: an off-grid desalination-equipment group wants to move the engineer who designed its proprietary membrane-monitoring settings to a related U.S. company. The first review should name the knowledge in concrete terms, identify where it is recorded, and show how the engineer acquired it through the foreign employment. Training slides, version histories, and internal problem reports can establish that the knowledge belongs to the business rather than the profession generally. The role description must then explain which U.S. decisions require that knowledge and why ordinary engineering experience would not substitute.